This invention relates to both general purpose and special purpose syringes in which an attached needle assembly is exposed during use. Since concern for blood borne diseases is particularly acute today, various procedures have been proposed to lessen or eliminate the chances for the needle to accidentally stick those using the syringe during various medical procedures in which the syringe is passed back and forth as between a doctor/nurse and assistants. The same general concerns relate to both standard hypodermic needle syringes for general use as well as syringes particularly designed for dental use.
Specifically in regard to dental use, the current practice for injecting a local anesthetic into a patient and the subsequent handling of the needle is as follows:
The dental assistant screws a needle into the sterilized syringe. The needle used is double ended. i.e., a "long" end which is inserted into the patient and a "short" end which is forced through a membrane, i.e., a surgical rubber plug, and into a cartridge containing local anesthetic. The hub of the needle can be plastic or aluminum. Both ends of the needle are capped. The assistant removes the cap from the short end of the needle and screws it onto the threaded end of the syringe.
The assistant then inserts a cartridge containing the local anesthetic into the syringe. The plunger is spring loaded and by pulling out on the plunger, sufficient space is made to insert the cartridge. When the plunger is released, the short end of the needle pierces the membrane in the bottom of the cartridge allowing the local anesthetic to be released when pressure is applied to the plunger. The syringe is now ready for use. The cap on the long end of the needle is removed exposing the needle. The dentist can now make the stick.
After the stick is made, one of two things can happen: 1) no more injections are needed for this patient, and the needle must be thrown away; or b) additional injections are needed and then the needle is thrown away. If this specific patient is to have further injections, then the needle is recapped, handed to the assistant (or handed to the assistant and then recapped) so that a new cartridge can be inserted into the syringe. The same procedures as outlined above are followed. In some cases, the dentist can forget to recap the needle and will leave the exposed needle on the work surface.
Once the new cartridge is inserted, the syringe is now handed back to the dentist and the cap removed (or the cap is removed and then handed back to the dentist). The new stick can now be made.
Once all sticks are done, the needle must now be removed and disposed of in the sharp container. The first step is to recap the needle. Once recapped by the dentist, the syringe is handed to the assistant (or it is handed to the assistant and then recapped).
It thus can be seen that extensive needle exposure is present in this system and the passing back and forth of such devices could easily result in accidental sticks. However, there is widespread use of this system, and it is popular. Accordingly, it would be desirable to provide a device which reduces exposure to accidental sticks yet continues to utilize this general system.
Similarly with respect to a standard hypodermic needle, the uncapped point thereof is exposed during passage between doctors and assistants in a similar fashion; and, accordingly, it would also be desirable to provide a device which reduces such exposure to accidental sticks with respect to standard hypodermic needle syringes as well.
These and other objects of the present invention are accomplished by the provision of a device for the safe handling of hypodermic syringes of the type having a hollow cylindrical body for containing fluids with opposed forward and rear ends with a needle assembly mounted at said forward end and including a forwardly projecting normally exposed needle, and an injection assembly mounted at said rear end and including a hand-manipulatable, longitudinally-movable piston for injecting fluid housed in said body through said needle and into a patient, said device including a tubular safety sleeve having an inner diameter slightly larger than that of the hollow cylindrical body of the syringe and adapted for telescopic mounting over said body and further adapted for back and forth forward to rearward sliding movement therein from a full rearward position wherein said needle is exposed to a full forward position wherein said needle is housed within the confines of said sleeve and thus protected from coming in contact with users or patients and means associated with said safety sleeve for limiting the forward and rearward motion of said sleeve vis-a-vis said syringe.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.